High-temperature grease compositions



Patented Sept. 15, 1953 UNITED STATES PATENT OFFICE HIGH-TEMPERATUREGREASE COMPOSITIONS Loren C. Bollinger, Mar- Harold A. Woods and tinez,Calif., assigno Company, Delaware to Shell Development Emeryville,Calif., a corporation of N Drawing. Application December 29, 1951,

Serial No. 264,233

forms a colloidal dispersion in the lubricating oil base. Such greasesare unsuitable for use in the lubrication of bearings operating atelevated temperatures such as those used in aircraft mechanisms and thelike.

Greases have been proposed to overcome certain disadvantages of thisnormal type of grease; U. S. Patent No. 2,182,137 to Veron L. Rickettsdescribes such greases. In the greases described in the Ricketts patent,use in made of certain salts of aromatic acids such as sodium benzoatewhich apparently form complexes with the normal soap-forming acids.Greases containing these ingredients exhibit exceptionally high droppingpoints and, hence, are suitable for use at elevated temperatures.However, as Ricketts notes, it was necessary to heat such greasecompositions to a temperature of at least 500-600 F., preferably 550-600F. in order to produce a satisfactory grease structure. The lubricatingoil base employed by Ricketts in the production of his greases was amineral oil. It will be realized that operations involving temperaturesin the order of 500-600 F. involves fire hazards necessitating the useof special precautions. This is true even if high flash point mineraloils are employed.

It is an object of the present invention to produce improved greases. Itis a particular object of this invention to produce improved greases foruse at elevated temperatures. A special object of this inventioncomprises the production of high temperature greases at temperaturesbelow those involving excessive fire hazards. Other objects will becomeapparent during the following discussion.

Now, in accordance with the present invention, it has been found thatthe disadvantages of high temperature grease cooking can be avoided andthe life of the grease unexpectedly prolonged by the use of alubricating oil base comprising a special mineral oil having a viscosityof between about 1250 and about 11,000 SUS at 100 F., said oilcontaining less than about by weight of aromatic hydrocarbons, combinedwith a greater amount of a compatible synthetic high boiling liquidpolyorganosiloxane having a viscosity within the lubricating oilViscosity range.

Still in accordance with the present invention it has been discoveredthat the addition of high molecular weight alcohols, and particularlypolycyclic alcohols, unexpectedly promotes the high temperatureoperating life of these greases.

Greases prepared according to the present invention comprise as theliquid base a mixture of the special mineral oil and polyorganosiloxane,said mixture containing a major proportion, from about 55% to about 95%by Weight of the latter and a minor proportion of at least 5%, fromabout 5% to about 45% by weight, of said mineral oil, the percentagesbeing based on the mixture. This mixture of lubricating oils isthickened to a grease consistency by means of a soap predominating insodium soaps of at least one carboxylic acid having or more carbonatoms. These acids may be aliphatic acids or cycloaliphatic, such asfatty acids or naphthenic acids. Moreover the greases must contain analkali metal salt of an organic carboxylic acid containing an aromaticring. The

description and proportions of these ingredients will be discussedbelow.

THE MINERAL LUBRICATING OIL While the present invention is not to beconfined to the use of a mineral oil derived from any particular sourceor by any particular refining process, the usual source of suitablemineral oils comprises the fraction thereof generally termed brightstock, and bright stocks having a viscosity index of at least 60. Theterm bright stock is one which is well recognized in the art of refiningmineral oils. To obtain the desired fraction, crude oils containinglubricating oil components are usually subjected to distillation underordinary atmospheric pressures in order to obtain a long residuecomprising the fraction which does not distill under these conditionswithout substantial decomposition. The long residue is then subjected todistillation under reduced pressure, with or without steam. Under theseconditions, gas oil and waxy lubricant fractions distill over, leavingwhat is normally termed a short residue or a steam refined stock, alsoknown as cylinder stock. This material is then deasphalted (if anasphalt-containing crude is employed), then solvent extracted toseparate paraflinic and naphthenic components from aromatic components,and the rafiinate therefrom is then subjected to dewaxing operations toremove microcrystalline and/or macrocrystalline waxes. The solventextraction and dewaxing operations may be reversed in order if desired.Clay contact treatment or percolation may be employed to clean up theoil following any one or all of these separate operations. The raflinatewhich remains after deasphalting, dewaxing, extraction, and claytreatment is generally called bright stock.

The bright stocks which are suitable for use in the present compositionshave the ranges of properties shown in Table I.

TABLE I Properties of bright stocks Visc. SUS, 100 F. 1250, usually'1250-11,000,

preferably 1500-3500 Visc., SUS, 210 F. 75, usually 125-325, preferably150-250 Viscosity Index (Dean and Davis) +60, preferably +85 to 130Aniline point, C. 100, preferably 115 Flash, F. 475, preferably 500Fire, F. 550, preferably 600 Pour point, F. maximum 25, preferably lowerthan 15 Aromatics, per cent wt. 15, preferably (optimum 5) Naphthenes,per cent wt. 35

Paraifines, per cent wt. at least 60 The properties of typical brightstocks which are useful in the compositions of this invention are givenin Tables II and III.

The most important inherent properties of a mineral oil suitable for thepresent use comprise the volatility, oxidation stability, aromaticcontent and the viscosity characteristics. The aromatic content has alarge influence upon the sensitivity of the oil to thermal changes andthe viscosity of the oil defines its suitability for the presentpurpose. Hence, the best definition with respect. to essentialcharacteristics of mineral oil suitable for the present compositions isthat it comprises those oils having an aromatic hydrocarbon. contentless than about 15% by weight and: having a viscosity of between about1250 and about 11 ,000 SUS at 100 F. Having defined these particularproperties, the other properties such as flash, fire, and anilinepoints, and viscosity index usually are largely dependent upon them.

wherein the units are attached through the silicon and oxygen atoms andwherein. R and R" represent alkyl, aryl, alkaryl, aralkyl, andcycloalkyl groups. The method of producing these TABLE II Examples oftypical bright stocks:

g gg Ring Analysis AV Ratio fi Rings A N P PIN Wt. fi l r; ,per- ,pero.100 210 VI percent cent cent Mid-ContinentMildExtraction. 3,650 1.64 771a 1 17 70 411 685 3.7 Mid-Continent Conventional Extraction 2,569 141as 9 19. 72 as 685 3.4 Mid-Continent Heavy Extxaev tion 2,049" 131 93 3'21 76 3.6 675 2.9 144 102. 5 1s 79 4.9 730 3.0 Gulf CoastaL. 85 63 4 35.61 1. 7 515. 3. 4

1 Ar.=aromatics, N==naptl1enes, P=paraflins;

TABLE III. polymers is well known, and may involvev the.-specifimfiomjor typicazMimcontment bright reaction of a s1l1con halide wth a Grignard stocks reagent to form the corresponding organo s1l1- conhalide, followed by hydrolysis of the organo Unpem; may silicon halideto form a silicol, and then. conlated. Percolated densation of thesilicol in the presence of air or oxygen, with the aid of a catalyst orheat to Gravity, API, min 24.5 25.5 form the polyorganosiloxane orsilicone polymer ggg l 313i: g f fffef 5 (Kipping, Proc. Chem. Soc. 20,15-16 (1904)).-.De- Flash F, .515 pending upon the extent. ofcondensation or polytt'. ettin moi-t8 merizaiion, the resulting Productsvary fmm Viscosity Index, min relatively light liquids to solid resinsand are reported to be both chain-like (Rochow-U. S.

It will be understood from the above. analyses that the source ortreatment of. a particular mineral oil is not as important for thepresent purpose as the final properties of the mineral oil constituentto be used in these compositions. For example, it is possible to varythe extent of solvent extraction dependent upon. the original aromaticcontent and the requirements. of the specific use of the final product,as well as upon the necessity or desirability of deasphalting, claytreating, acid treating, and the like. Hence, it will be recognized thatthe present. invention is predicated upon the use of a mineral oilfraction having the above. defined. ranges of. properties and not uponthe source or treatment of such oil.

Patent No. 2,352,974) and cyclic (Hyde-U. S.

Patent No. 2,371,050) in structure. For purposes.

While any of the various types of silicone polymers within the foregoingdefinition are contemplated for purposes of the present invention, thepreferred polymers, from the standpoint of cost, are those which haveachieved the greatest commercial production, namely, the dimethylsilicone polymers, the diethyl silicone polymers, and the ethylphenyl ormethylphenyl silicone polymers. However, the silicone polymers havinghigher radical weight alkyl groups, such as butyl, amyl and higher,constitute suitable lubricant bases for purposes of the presentinvention. In general, these siliconepolymers are adapted tospeciialized lubrication outside the conventional lubricatingtemperature ranges, such as ultra low temperature operation found inrefrigerator systems and arctic service, or to generalpurposelubrication over a wide lubricating temperature range which waspreviously unattainable through the use of a single mineral lubricatingoil because of the latters high viscosity change over such a widetemperature range. In addition, these silicone materials are compatiblewith bright stock mineral oils and more resistant at high temperaturesWhere hydrocarbons, esters of carbon chain compounds and similarsynthetic lubricant bases of essentially organic structure are subjectto carbonization such that they eventually become dry and hard.

THE GREASE-FORMING SOAP The soda soap comprising the major greaseformingingredient should constitute from about 2% to about 40% by weight of thecomposite grease. The term soda soap, as used in the presentspecification and claims, designates sodium soaps of carboxylic acidscontaining at least about 20 carbon atoms. Particularly outstandingresults are obtained by the use of acids present in beeswax or degras.While the major greaseforming component should comprise sodium soaps ofsuch acids, minor amounts of other soaps may be present to goodadvantage for particular purposes.

Acids finding favored use for the formation of soda soaps in the presentgreases comprise the following:

Phthioic acid Tetracosenoic acids (e. g., selacholeic acid) Docosenoicacids (e. g., erucic acid) Eicosenoic acids (e. g., gadoleic acid)Arachidonic acid Clupanodonic acid Lignoceric acid Selacholeic acidCeloleic acid Melissic acid Montanic acid Cerotic acid Behenic acidn-Octatriacontanoic acid In addition to the use of higher aliphaticacids, such as those enumerated above, high molecular weight naphthenicacids may be used in place of or in addition to those already specified.Petroleum naphthenic acids having more than 20 carbon atoms per moleculemay be employed.

AROMATI C SALTS Salts of both light and heavy metals may be employed butit is preferred to employ oil soluble salts of alkali or alkaline earthmetals and an v up to about 30 carbon atoms.

organic carboxylic acid containing an aromatic ring. The salt shouldhave the formula:

R(|OM wherein M is a hydrogen equivalent of the metal and R representsan organic radical containing an aromaic ring which may or may not besubstituted with hydrocarbon and/or non-hydrocarbon groups. Thecarboxylate residue,

-r i-o-M may be linked directly to a carbon atom of the aromatic nucleusor it may be linked thereto through an aliphatic or oxyaliphaitc atom orgroup of atoms, such as a chain of atoms. This chain may be saturated orunsaturated and the acid radical may be substituted with polar radicalssuch as halogen, amino, hydroxy, keto, or other polar groups. Thepreferred acids include hydrocarbon monocyclic aromatic and.alkylaromatic acids, such as benzoic, 0-, mand p-toluic acids, the xylicacids (e. g., 2,4-, 2,5-, 2,6-dimethylbenzoic acids) hydrocarbondicyclie aromatic and alkylarornatic acids, that is the naphthoic acidsand alkylnaphthoic acids (e. g., anaphthoic acid, [r-naphthoic,4butyl-1-naphthoic acid), hydroxy substituted aromatic acids (e. g.,salicyclic acid, 3,5-diisopropyl-l-hydroxybenzoic acid) and arylaliphatic acids such as phenyl acetic acid, cinnamic acid, a-naphthylacetic acid. Suitable salts made therefrom include sodium benzoate,potassium cinnamate, lithium salicylate, calcium xylate and magnesiumvinylate.

Other aromatic acids which may be employed include phenyl acetic, toluicand other alkyl benzoic acids. Phenyl propionic, naphthoic, butylnaphthoic, and phenyl monobasic acids may be employed to form sucheffective salts as sodium phenyl acetate, sodium toluate, potassiumhydrocinnamate, aluminum naphthoate and zinc naphthylacetate.

The salt utilized in the composite greases, according to the presentinvention, is preferably present in concentrations between 0.1% andabout 6% by weight although higher concentrations may be employed. Thesalt may be formed apart from the step of saponification of thealiphatio material employed for the grease base, and added to the soapeither before or after the admixture with the special mineral oil andpolyorganosiloxane while the mixture .is being heated; it may, however,also be formed in the same operation as explained below in the specificexamples.

HIGH MOLECULAR WEIGHT ALCOHOLS In addition to the essential ingredientsenumerated hereinbefore, outstanding mechanical stability is obtained bythe addition of high molecular Weight alcohols, and particularlymonohydric alcohols, to these compositions. These alcohols should haveat least 12 carbon atoms and include aliphatic alcohols such as lauryl,cetyl, stearyl, heptadecyl, and monodecyl alcohols; the correspondingmono-olefinic alcohols such as oleyl alcohol and poly olefinic alcoholssuch as linoleyl alcohol, and cyclic alcohols including monoandpolycyclic alcohols, such as naphthenic alcohols. The preferred. type ofalcohol for use in these compositions comprises the polyalicyclicalcohols (such as those found in wool fat) which contain at least about17 and The principal component of wool fat alcohols is believed to becholestanol. Other suitable polycyclic alcohols: promoting, themechanical stability of the present greases include the following:

Allochlolesterol Ostreasterol Lanosterol.

Lanyl alcohol Lano-octadecyl alcohol Cholesterol 'I-dehydrocholesterolAlpha-spinasterol Fucasterol Stigmasterol Beta-sitosterol ErgosterolErgostanol Alcohols such as those described above may be used in amountsof about 1-5%, based upon the weight of the total grease composition.Preferably they are present in amounts of from about 1.5 to about 3%based on the total grease but this proportion will vary with thespecific requirernents of the grease and the other ingredients present.The presence of these alcohols, such as wool fat alcohols, reduces thegranularity of the grease, prevents bleeding and depresses slumpability.All of these properties enhance the mechanical life of the grease duringits utilization for such purposes as bearing lubrication. Theseproperties will be evident from the data presented hereinafter.

Summarizing the compositions, as described above, the preferred greasescontain the following ingredients in the stated proportions:

Weight percent Polyorganosiloxane 55-95% of mixture Special mineral oil51-45% of mixture} Balance In addition to the above essential oroptional ingredients, other materials may be present. For example, thelubriacting oil base (comprising 5-45% of the special mineral oil and55-95% of the polyorganosiloxane) may be supplemented by the presence ofother types of lubricants in minor amounts such as aliphatic diesters,e. g., bis(2- ethylhexyDsebacate; phosphate esters such as tricresylphosphate; phosphonates such as diethyl benzene phosphate and the like.

The soda soap may be supplemented by the presence of less than about 5%based on the total soap content of other soaps such as the potassium orcalcium soaps of the same or different acids including the potassiumsoaps of beeswax acids 'or the calcium soaps of degras. The presence ofsuch minor amounts of nonsodium soaps promotes the mechanical stabilityof the greases.

Supplementing the beneficial action of the salts of aromatic acids andthe high molecular weight alcohols, various types of antioxidants,anti-corrosion agents and extreme pressure agents may be present. Aparticularly effective type of antioxidant comprises aromatic aminespreferably containing at least carbon atoms. These may be eithermonocyclic or polycyclic although the naphthalamines: are preferred.

Typical species of these include phenyl alphanaphthylamine, phenylbeta-naphthylamine and benzyl phenyl naphthylamine. Other suitableamines include dilp-aminophenyl) phenyl methane, and polyalkyl diaminodiaryl alkanes such 8 as 'P,P(N,N tetra-methyl) diamino diphenylmethane.

A synergistic action has been observed to occur when both an aromaticamine and a reaction product of a terpene with a phosphorous sulfide arepresent. The latter type of reaction product is described in the patentliterature and comprises the product obtained by heating a phosphoroussulfide and a dicyclic terpene together at a temperature above. about212 F. Suitable sulfides include the mixtures of various phosphoroussulfides but phosphorous pentasulfide is especially preferred and pineneor turpentine are effective species to be reacted therewith. Thereaction is carried out usually between temperatures of 212-320 F. witha ratio of 1 mol of phosphorous sulfide to about 3-5 mols of thedicyclic. terpene.

In addition to these especially effective in.- gredients, another classstill further improving the compositions comprises the metallic salts ofcarbamic acid or its analogs. Species of these materialsinclude the zincor calcium salts of dibutyl dithiocarbamic or of dihexyl dithiocarbamicacid as well as the strontium, zinc or lithium salts of dibenzyl mono--or dithiocarbamic acid. Generally these additives are present in anamount less than 5% by weight of the composition and if present ineffective quantities comprise at least about 0.1% by weight of the totalcomposition.

Other additives which may be present include pour point depressants,viscosity index improvers, and alkali metal soaps of hydroxy fatty acidshaving more than 12 carbon atoms per molecule such as 0.1-2.5lithium-12-hydroxy stearate.

The following compositions illustrate the basic compositions of thepresent invention. In preparing these compositions, it has been found,as noted already, that the combination of the two essential oils makespossible the use of much lower cooking temperatures than was possibleheretofore. While the exact reason for this is somewhat obscure, it isbelieved that the presence of substantial quantities ofpolyorganosiloxane promotes melting or dissolution of the soap and saltat lower temperatures than are required when the lubricating oil isentirely composed of a petroleum base. While the individual steps may bealtered in accordance with well-known variations in the art, thefollowing procedure is preferred since it produces greases havingmaximum mechanical stability bothunder dynamic and static conditions:Part of the mixture of special mineral oil and polyorganosiloxane isheated to a temperature of approximately F. At this initial elevatedtemperature the high molecular weight acids, such as beeswax acids, areadded and stirred until melted. The mixture is then warmed to about 230F. The acids are saponified at about this temperature by the addition of33% aqueous sodium hydroxide solution. The resulting mixture is heated(to gradually eliminate water and complete saponification) to atemperature of about 300 F. and held at this emperature forapproximately one hour. Thereafter the composition is cooled to about195 R, while being stirred, after which high molecular weight alcohols,e. g., wool grease alcohols, and aromatic acids are added together witha minor amount of water, such as about 1% based on the finished grease.The mixture is again heated to about e250 F. and held at thistemperature for approximately'thirty minutes. The batch is then cooledby the addition of the remainder of the mixture of oils to a temperatureof about 250 F. and the alkalinity adjusted to approximately 0.1- 0.3%sodium hydroxide by adding either sodium hydroxide or benzoic acid.Other additives, as desired, are incorporated at this point. The finalgrease is then homogenized and cooled to obtain the completed product.

As noted hereinbefore, each of these steps is subject to variationdependent upon the identity of the ingredients employed. For example,the initial period of heating may be to temperatures between about 170and 225 F. in order to melt the particular species of acids utilized orto increase or depress the rate of melting of said acids. Thetemperature of saponifioation also may be varied from approximately 200to about 250 F.; the rate of caustic addition may be used as one meansof controlling this temperature. The heat of saponification, as well asexternal heat, may be used for this effect. The maximum saponificationtemperature will vary according to the species of acid used but willordinarily be between about 275 to 325 F. This maximum temperature maybe held for periods from about thirty minutes to about four hours. Thetem perature following maximiun cooking temperature may be lowered to175275 F. The salts of benzoic acids, or other aromatic acids, may beadded in pre-formed state or the acids can be saponified during or aftertheir addition to the grease-forming ingredients. Hence, sufficientcaustic may be added in the previous saponification step to saponify thearomatic acid or additional caustic may be supplied during or subsequentto the acid addition. The maximum cooking temperature will vary with theexact proportion of polyorganosiloxane and special mineral oil but inall instances it will be found that this usually is from 50 to 150 F.lower than that required if the lubricating oil base were all mineraloil. This maximum cooking temperature will be between about 400 and 475F. and will be held for a period varying from about 15 minutes to about2 hours.

Addition of the balance of the oil maybe at such a rate and in suchproportions as to cool the composition to a temperature between about150 and about 250 F. in order to blend in any other additionalingredients. It will be understood that the proportion of oil initiallyadded to the cooking vessel will be selected depending satisfactorily bythe use of maximum cooking temperatures in the order of about 400-475 F.Example 1:

10% sodium beeswax soaps 3% sodium benzoate 3% cetyl alcohol 74%dimethyl silicone fluid 10% bright stock Example 2:

10% sodium degras soaps 3% potassium cinnamate 3% branched (Zia-C18aliphatic alcohols 67% dimethyl silicone 17% bright stock Example 3:

15% sodium cerotate 2.5% lithium salicylate 2.5% cholestanol dimethylsilicone 20 bright stock Example 4:

9 sodium beeswax soaps 1% potassium beeswax soaps 80% dimethyl silicone10% bright stock Example 5:

19% sodium beeswax soaps 1% calcium beeswax soaps 68% dimethyl silicone12% bright stock Example 6: Greases were prepared using the procedureoutlined above and in accordance with the ingredients specified in TableIV. These were tested in two accepted dynamic test rigs as follows: TheAnnular Bearing Engineers Committee Test (ABEC Test) at 400 F. and theNavy Engineering Experiment Station Test at 392 F. The first of these isdescribed in detail in Technical Bulletin No. 5 of the NationalLubricating Grease Institute Cooperative Committee dated November 1944.The latter test is described in the Federal Stock Catalogue datedNovember 15, 1948, Serial No. V V-L-791d and is Method No. 33.1. Thistest is used by the Navy Experiment Station in grease investigations.While it is operated at a somewhat lower temperature than the firsttest, the grease is exposed to a greater quantity of air and istherefore subject to more stringent conditions in regard to evaporationand oxidation.

TABLE IV Wt P "Vt P Wt P ABEC 73%? er- 1 orer- .1. Grease cent cent ggiif g' 2923 cent Wool Test, Bearing Bright Dimethyl Beeswax BenzoateGrease Hours at Test Stock Silicone Alcohols 400F Hours at upon thedegree of ease required in stirring or otherwise working the batch. Withthe greases given in the following examples approximately one-half ofthe oil mixture was initially employed although quantities betweenone-fourth and all of the oil may be added initially to the cookingkettle. Using the method as outlined about the following greases can beprepared and are found to have exceptionally high mechanical stabilityAccording to Table IV, it will be found that the use of both dimethylsilicone and bright stock resulted in a grease having a Navy BearingTest life nearly three times as great as when bright stock alone wasemployed. However, the major improvement gained by the combination ofsilicone with bright stock comprised the substantially lower temperature(in the order of about F. lower) required for the maximum cooking aswell as exhibiting the property of being formed 75 temperature in orderto obtain satisfactory zgasaeei greases as compared with the much highertemperatures required when bright stock alone was the lubricating oilbase. Attention is directed to the outstanding improvements obtained bythe addition of wool grease alcohols and particularly to the response asillustrated by the Navy Bearing Test for grease F. It would be expectedby examination of greases D and 'E that the Navy Bearing Test life ofgrease F would have been about 100 hours :or less. However, it was foundthat the test life was about .18 1 hours. Hence, this is 'a cleardemonstration of a synergistic effect apparently occurring when brightstock and silicone fluidlare combined with wool grease alcohols inaddition to the benzoic acid salt and soaps of'beeswax acids. Similarunexpected properties can be demonstrated with the compositions ofExamples 1 to 5.

Other specific compositions which are preparable in accordance with thepresent invention include the following:

Example '7:

Weight percent Dimethyl silicone fluid 70 Bright stock 12 Sodium soap ofbeeswax acids 11 Sodium benzoate 3 Phenyl alpha-naphthylamine l Woolgrease alcohols 3 Example 8:

Dimethyl silicone fluid 69.5 Bright stock 12 Sodium soap of beeswaxacids 11 Sodium benzoate 3 Phenyl alpha-naphthylamine 0.5 P2535 reactionproduct with turpentine 1 W001 grease alcohols 3 Example 9:

Dimethyl silicone fluid 69 Bright stock '12 Sodium soap of beeswax-acids11 Sodium benzoate 3 Phenyl alpha-naphthylamine 0.5 P2515 reactionproduct with turpentine 1 Zinc dibutyl dithiocarbamate 0.5 Wool greasealcohols 3 Example Dimethyl silicone fluid 68 Bright stool: 12 Sodiumsoap of beeswax acids 11 Sodium benzoate 3 Phenyl alpha-naphthylamine0.5

P285 reaction product with turpentine 1 Zinc dibutyl dithiocarbamate 0.5Dilauryl selenide 1 W001 grease alcohols 3 1. A lubricating greasecomposition comprising as the lubricating base thereof a mixture of from55% to about 95% by Weight of a synthetic high boiling liquidpolyhydrocarbylsiloxane having a viscosity within the lubricating oilviscosity range and from about 5% to about 45% by Weight of a minera1oil having a viscosity of between about 1250 and about 11,000 SUS at 100said mineral oil containing less than about 15% by weight of aromatichydrocarbons, the lubricating base being thickened to a greaseconsistency by a sodium soap of a carboxylic acid having at least 20carbon atoms per molecule, said grease containing a minor proportion ofan alkali metal salt or" an organic carboxylic acid containing anaromatic ring.

v2. A lubricating grease composition comprising as the lubricating basethereof a mixture of from 55% to about 95% by Weight of a high boilingliquid dialkyl silicone polymer having a viscosity within thelubricating oil viscosity range and from 5% to about 45% by Weight of amineral oil having a viscosity of between 1250 and about 11,000 SUS at100 F., said oil containing less than about 10% by-Weight of aromatichydrocarbons and having a viscosity index greater than about '60, thelubricating base being thickened to a grease'consistency by a sodiumsoap of an aliphatic monocarboxylic acid having at least 20 carbon atomsper molecule, said grease containing a minor proportion of a sodium soapof an organic carboxylic acid containing an aromatic ring and apolycyclicalcohol.

'3. A lubricating grease composition comprising as the lubricating basethereof a mixture of from 55% to about 95% by weight of a high boilingliquid dimethyl silicone polymer having a viscosity within thelubricating oil viscosity range and from about 5% to about 45% by weightof a mineral oil having a viscosity of between about 1250 and 11,000 SUSat 100 F., said oil containing less than about 10% by weight of aromatichydrocarbons and having a viscosity index greater than 60 and an anilinepoint higher than about 100 0., the lubricating base being thickened toa grease consistency by a sodium soap of a 'monocarboxylic aliphaticacid having at least 20 carbon atoms per molecule, said greasecontaining a minor proportion of a sodium salt of an organic carboxylicacid containing an arcmatic ring and a minor proportion of at least one=sterol.

4. A lubricating grease composition comprising as 'thelubricating basethereof a mixture of from 55% to about 95% by weightof a high boilingdimethyl silicone polymer having a viscosity within the lubricating oilviscosity range and from about 5% to about 45% by weight of a mineraloil having a viscosity between about 1500 and about 3500 SUS at 100 F.,said oil containing less than about 10% aromatic hydrocarbons and havinga viscosity index greater than about and an aniline point higher thanabout 115 C., the lubricating base being thickened to a greaseconsistenc by a sodium soap of beeswax acids, said grease containing aminor proportion of sodiumjbenzoate and of wool fat alcohols.

5. A lubricating grease composition comprising as the lubricating basethereof a mixture of from 55% to about by weight of a synthetic highboiling polyhydrocarbylsiloxane having a viscosity within thelubricatingoil viscosity range and from about 5% to about 45% by weight of amineral oil having a viscosity of between about 1250 and 11,000 SUS atF., said lubricating oil containing less than about 15% by weight ofaromatic hydrocarbons, the lubricating base "being thickened to a greaseconsistency by a sodium soap of an organic carboxylic acid having atleast 20 carbon atoms per molecule and containing minor proportions ofan alkali metal salt of an organic carboxylic acid containing anaromatic ring and an alcohol having at least 12 carbon atoms permolecule.

6. A lubricating grease composition comprising as the lubricating basethereof a mixture of from about 55% to about 95% by weight of asynthetic high boiling dialkyl silicone polymer having a viscosit withinthe lubricating oil viscosity range and from about to about 45% byweight of a mineral oil having a viscosity of between about 1250 and11,000 SUS at 100 F., said oil containing less than about by weight ofaromatic hydrocarbons and having a viscosity index greater than about60, the lubricating base being thickened to a grease consistency by asodium soap of an aliphatic carboxylic acid having at least 20 carbonatoms per molecule and containing a minor proportion of a sodium salt ofan organic carboxylic acid containing an aromatic ring.

7. A lubricating grease composition comprising as the lubricating basethereof a mixture of from 55% to about 95% by weight of a liquid highboiling dimethyl silicone polymer having a viscosity within thelubricating oil viscosity range and from about 5% to about 45% by weightof a mineral oil having a viscosity of between about 1250 and about11,000 SUS at 100 F., said oil containing less than about 10% by weightof aromatic hydrocarbons and having a viscosity index greater than 60and an aniline point above about 100 C., the lubricating base beingthickened by sodium soaps of beeswax acids, the grease containing aminor proportion of sodium benzoate.

8. A lubricating grease composition comprising as the lubricating basethereof a mixture of from 55% to about 95% by weight of a high boilingliquid dimethyl silicone polymer having a viscosity within thelubricating oil viscosity range and from about 5% to about 45% of amineral oil having a viscosity of between about 1500 and about 3500 SUSat 100 F., said oil con taining less than about 10% by weight ofaromatic hydrocarbons and having a viscosity index greater than about 85and an aniline point above about 115 C., the lubricating base beingthickened to a grease consistency by sodium soaps of degras, said greasealso containing a minor proportion of a sodium salt of an organiccarboxylio acid containing an aromatic ring.

9. A lubricating grease composition comprising as the lubricating basethereof a mixture of 55% by weight to about 95% by Weight of a highboilin liquid dimethyl silicone polymer having a viscosity within thelubricating oil viscosity range and from about 5% to about 45% by weightof a mineral oil having a viscosity of between about 1500 and about3.500 SUS at 100 F., said oil containing less than about 10% aromaticand having a viscosity index greater than about 85 and an aniline pointhigher than about 115 C., the lubricating base being thickened to agrease consistency by a sodium soap of beeswax acids, said grease alsocontaining minor proportions of sodium benzoate and cholestanol.

10. A lubricating grease composition comprising as the lubricating basethereof a mixture of from about 55% to about 95% by weight of asynthetic high boiling liquid dimethyl silicone polymer having aviscosity Within the lubricating oil viscosity range and from about 5%to about 45% by weight of a mineral oil having a viscosity of betweenabout 1250 and about 11,000 SUS at 100 F., said oil containing less thanabout 10% aromatic hydrocarbon and having a viscosity index greater thanabout 60, the lubrieating base being thickened to a grease consistencyby a mixture of sodium and potassium soaps of higher aliphaticmonocarboxylic acids wherein the potassium soaps constitute less thanabout 5% by Weight of the total soap content, said sodium soaps beingsoaps of acids containing at least 20 carbon atoms per molecule, said'grease also containing minor proportions of an alkali metal salt of anorganic carboxylic acid containing an aromatic ring and of at least onesterol.

11. A lubricating grease composition comprising the lubricating basethereof a mixture of from about 55% to about by weight of a synthetichigh boiling liquid dimethyl silicone polymer having a viscosity withinthe lubricating oil viscosity range and from about 5% to about 45% byWeight of a mineral oil having a viscosity of between about 1250 andabout 11,000 SUS at F., said oil containing less than about 10% aromatichydrocarbon and having a viscosity index greater than about 60, thelubricating base being thickened to a grease consistency by a mixture ofsodium and calcium soaps of higher aliphatic monocarboxylic acidswherein the calcium soaps constitute less than about 5% by weight of thetotal soap content, said sodium soaps being soaps of acids containing atleast 20 carbon atoms per molecule, said grease also containing minorproportions of an alkali metal salt of an organic carboxylic' acidcontaining an aromatic ring and of at least one sterol.

12. The process for the preparation of grease compositions whichcomprises heating a synthetic high boiling liquid dimethyl siliconepolymer having a viscosity within the lubricating oil viscosity rangeand a mineral oil having a viscosity of between about 1250 and 11,000SUS at 100 F., said oil containing less than about 10% aromatichydrocarbons and having a viscosity index greater than about 60 togetherwith beeswax and benzoic acid to a temperature between about and 225 F.,saponiiying the beeswax and benzoic acid with a sodium alkali base at atemperature below 250 F., dehydrating the resulting mixture attemperatures between about 275 F. and about 325 F. for a period betweenabout one-half and about four hours, cooling to a temperature of betweenabout F. and about 275 F., adding W001 grease alcohols at a temperaturewithin the latter range, heating the resulting composition to atemperature between about 400 F. and 475 F. for a period between aboutone-fourth and two hours and cooling the resulting grease composition,the silicone polymer and mineral oil mixture being present in the finalgrease compositions in proportions between about 55-95 parts by weightof the polymer and about 4.5-5 part by weight of the mineral oil foreach 100 parts by weight of the mixture.

13. The process for the preparation of grease compositions whichcomprises heating a synthetic high boiling liquidpolyhydrocarbylsiloxane having a viscosity within the lubricating oilviscosity range and a mineral oil having a viscosity of between about1250 and 11,000 SUS at 100 said oil containing less than about 15%aromatic hydrocarbons and having a viscosity index greater than about 60together with a carboxylic acid having at least 20 carbon atoms permolecule and an organic carboxylic acid containing an aromatic ring to atemperature between about 170 and 225 F., saponifying the carboxylicacid and organic carboxylic acid with a sodium alkali base .at atemperature below about 250 F., dehydrating :theresulting mixture-attemperatures between about 275 F. and about 325 F. for a period betweenabout one-half and about four hours, cooling to a temperature of betweenabout 1'75'and about 275 F., adding wool grease a1- cohols at atemperature within the latter .range, heating the resulting compositionto a temperature between about 400 F. and 475 F. for a period betweenabout one-fourth and two hours and cooling the resulting greasecomposition, the silicone polymer and mineral oil mixture being presentin the final grease compositions in proportions between about 55-95parts by weight of the polymer and about 45-5 parts by weight of themineral oil for each 100 parts by weight of the mixture.

14. .A lubricating grease composition comprising as the lubricating basethereof a mixture of from 55% to about 95% by weight of a synthetic highboiling liquid polyhydrocarbylsiloxane having a viscosity within thelubricating oil viscosity range and from about 5% to about 45% by weightof a mineral oil having a viscosity of betweenabout 1250 and about11,000 SUS at 100 F.; said mineral oil containing less than about byweight of aromatic hydrocarbons, the lubricating base being thickened toa grease consistency by a sodium soap of a carboxylic acid having atleast carbon atoms per molecule, said grease containing a minorproportion of an alkaline earth metal salt of an organic carboxylic acidcontaining an aromatic ring.

15. A lubricating grease composition comprising .as the lubricating basethereof a mixture of from to about .by weight of a synthetic highboiling liquid polyhydro carby-lsiloxane having a viscosity within thelubricating oil viscosity range and from about 5% to about 45% by weightof a mineral oil having .a viscosity of between about 1250 and about11,000 SUS at F.; said miner-aloil :containing less than about 15 byweight of aromatic hydrocarbons, the lubricating base being thickened toa grease consistency by a sodium soap of a carboxylic acid having atleast .20 carbon atoms per molecule, said grease containing :a minorproportion of an alkali metal salt of [an-organic monocyclic aromaticcarboxylic acid wherein the carbonyl radical is directly attached toacarbon atom of the aromatic ring.

HAROLD A. WOODS.

LOREN C. BOLLINGER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,182,137 Ricketts Dec. 5, 1939 2,407,037 Sowa Sept. 3, 19462,446,177 Hain et a1 1- Aug. 3, 1948 2,450,221 Ashburn et a1. Sept. 28,1948 2,456,642 Merker Dec. 21, 1948 2,508,741 Ashburn et a 'May 23, 1950

1. A LUBRICATING GREASE COMPOSITION COMPRISING AS THE LUBRICATING BASETHEREOF A MIXTURE OF FROM 55% TO ABOUT 95% BY WEIGHT OF A SYNTHETIC HIGHBOILING LIQUID POLYHYDROCARBYLSILOXANE HAVING A VISCOSITY WITHIN THELUBRICATING OIL VISCOSITY RANGE AND FROM ABOUT 5% TO ABOUT 45% BY WEIGHTOF A MINERAL OIL HAVING A VISCOSITY OF BETWEEN ABOUT 1250 AND ABOUT11,000 SUS AT 100* F., SAID MINERAL OIL CONTAINING LESS THAN ABOUT 15%BY WEIGHT OF AROMATIC HYDROCARBONS, THE LUBRICATING BASE BEING THICKENEDTO A GREASE CONSISTENCY BY A SODIUM SOAP OF A CARBOXYLIC ACID HAVING ATLEAST 20 CARBON ATOMS PER MOLECULE, SAID GREASE CONTAINING A MINORPROPORTION OF AN ALKALI METAL SALT OF AN ORGANIC CARBOXYLIC ACIDCONTAINING AN AROMATIC RING.